In maintaining water systems for recreational use a number of parameters have to be controlled. These factors include pH, alkalinity, and calcium concentration. Generally, a pH of 7.2-7.8, alkalinity within the range of 85-170 ppm, and calcium or magnesium hardness within the range of 140 to 250 ppm is desired for recreational waters.
In addition to the above it is important to provide clear and microbially safe water. Chlorine and other halogen based sanitization systems or products actually perform two tasks which are important to the upkeep of swimming pool and bathing waters.
The first task, sanitization, involves the biocidal or microbiocidal treatment of the pool water. Chlorine is a good sanitizer because it can penetrate the cell wall of microbiological agents and then destroy them.
The second task, involves providing water clarity by oxidizing dissolved or suspended matter in the water which can provide a nutrient source for pathogens. The unwanted matter include suntan oils, urea, leaves, soil and other matter introduced by the bathers or the wind.
Historically, chlorine has been successfully used as a treatment for both sanitization and as a water clarity agent because it is both a powerful biocide and oxidizing agent. However, the use of chlorine has fallen into disfavor because of environmental issues.
As an alternative to chlorine, quaternary ammonium compounds, such as the biguanides, and particularly the polyhexamethylene biguanides have become widely used as sanitizers for swimming pool water and other recreational water. Although these organic compounds are good microbiocides, they are not able to oxidize matter as required to provide water clarity. A 27.5% hydrogen peroxide has been used for that purpose because, like chlorine, it has the ability to oxidize organic compounds to forms which are more readily removed from the water. Hydrogen peroxide is also used because it is a powerful oxidizing agent. It is such a powerful oxidizing agent that this liquid can initiate combustion and cause burns to skin and eyes. However, it is not substantially reactive with the biguanides, which are oxidizable organic compounds.
In fact the biguanides are readily removed from pool water by oxidizing them with Oxone.RTM. peroxygen, 2KHSO.sub.5.K.sub.2 SO.sub.4.KHSO.sub.4, which is commonly used as an oxidizer to destroy biguanide in biguanide sanitized pools prior to instituting chlorine sanitization. Oxone provides about 4.5% active oxygen for this purpose. The active ingredient in Oxone is potassium monopersulfate, also known as potassium caroate, KHSO.sub.5. Oxone is a registered trademark of DuPont.
The persulfates have been used as oxidants for providing water clarity in conjunction with inorganic sanitizers such as chlorine, bromine, and chloro and bromo isocyanurates, but have not been used as an oxidant used in conjunction with organic sanitizers because of their similarity to the active ingredient of Oxone (potassium caroate), which is known to substantially oxidize organic sanitizers.